1. Field of the Invention
This invention relates generally to hand tools and more particularly to wrenches having automatic feed mechanisms to supply fasteners to their driving tip.
2. Description of the Prior Art
One of the most time consuming operations performed by assembly line personnel is the driving of fasteners. For example, to attach one subassembly to another it may be necessary to individually place a washer and then a lock washer over a number of threaded studs or bolts and then to thread and tighten a nut upon each one of the studs or bolts. Efficiency studies have indicated that, on the average, even an experienced assembler will require approximately thirty seconds to put a washer, lock washer and to fasten a nut upon a single stud. It may well be appreciated that this is a time consuming operation, and for example, should an assembly include twenty studs, the time required to fit a washer, lock washer and nut on all of the studs would be approximately ten minutes. This becomes quite expensive to the manufacturer due to the high cost of labor.
In order to speed up the process of driving fasteners, a number of prior art devices have been developed which automatically feed a fastener to the driving tip of a wrench. Such prior art devices, however, suffer from the disadvantage of being mechanically complex and relatively expensive. They further are not generally hand tools and usually require some type of external power source.
A further disadvantage of prior art wrenches having automatic feed mechanisms is that washers and lock washers, if they are needed, must still be manually placed upon a stud.